Chris L Pfalzgraff

US Patent:

54704456, Nov 28, 1995

Filed:

Apr 12, 1994

Appl. No.:

8/226785

Inventors:

James A. Murray - Walnut Creek CA
Michael R. Nees - Clayton CA
William P. Imrie - Layfayette CA
Christopher C. Rayner - Alamo CA
Chris L. Pfalzgraff - Concord CA
Robert K. Bates - San Ramon CA
Valmer H. Ness - Highlands Ranch CO
Terrance J. Cox - San Francisco CA

Assignee:

Bechtel Group, Inc. - San Francisco CA

International Classification:

C25C 706

US Classification:

204105R

Abstract:

In a tank confined electrolysis process, such as electrowinning or electrorefining, having circulated electroplating solution containing sulfuric acid, a multi-element cover system is applied below the electrode conductor connections and above the surface of the electrolyte bath. This cover is evacuated in the interstices below the cover and above the bath at a rate exceeding the stoichiometric ratio causing any leakage to occur into the volume overlying the bath thereby preventing acid aerosol from escape. The rate of evacuation is restricted so that humidity is maintain under the cover and over the surface of the bath to prevent the formation of crystals formed from aerosol droplets which become supersaturated. In a preferred embodiment, a circular weir in combination with gas discharge over the weir to a downcomer is disclosed. Entrainment of air over the weir and into the downcomer is disclosed to provide sufficient pumping for evacuation.

US Patent:

56097387, Mar 11, 1997

Filed:

Nov 27, 1995

Appl. No.:

8/563164

Inventors:

James A. Murray - Walnut Creek CA
Michael R. Nees - Clayton CA
William P. Imrie - Layfayette CA
Christopher C. Rayner - Alamo CA
Chris L. Pfalzgraff - Concord CA
Robert K. Bates - San Ramon CA
Valmer H. Ness - Hieblends Ramon CO
Terrance J. Cox - San Francisco CA

Assignee:

Bechtel Group, Inc. - San Francisco CA

International Classification:

C25D 702

US Classification:

204279

Abstract:

In a tank confined electrolysis process, such as electrowinning or electrorefining, having circulated electroplating solution containing sulfuric acid, a multi-element cover system is applied below the electrode conductor connections and above the surface of the electrolyte bath. This cover is evacuated in the interstices below the cover and above the bath at a rate exceeding the stoichiometric ratio causing any leakage to occur into the volume overlying the bath thereby preventing acid aerosol from escape. The rate of evacuation is restricted so that humidity is maintain under the cover and over the surface of the bath to prevent the formation of crystals formed from aerosol droplets which become supersaturated. In a preferred embodiment, a circular weir in combination with gas discharge over the weir to a downcomer is disclosed. Entrainment of air over the weir and into the downcomer is disclosed to provide sufficient pumping for evacuation.